Substrates with high rigidity are normally used as the substrates of semiconductor thin film and other thin film laminated bodies. However, flexible substrates of resins or similar materials are also used as the substrates of photoelectric conversion elements used in solar cells, for example, due to their light weight, ease of handling and other convenient features, as well as reduced costs through mass production.
As apparatuses for manufacturing thin film laminated bodies using such flexible substrates, film deposition apparatuses have been developed in which a strip-shape flexible substrate is passed through a plurality of film deposition chambers arranged consecutively, and an operation is repeated in which, while in a stopped state in each film deposition chamber, film is deposited onto the surface of the substrate, after which the substrate is transported to the position of the next film deposition chamber, to deposit a plurality of thin films with different properties onto the substrate (see, for example, Japanese Patent Application Laid-open No. 2005-72408).
Among such film deposition apparatuses, there are types which hold the strip-shape flexible substrate with the width direction extending in a horizontally and transport the substrate in a horizontal direction to perform film deposition, and also types which hold a strip-shape flexible substrate with the width direction extending vertically, and transport the substrate in a horizontal direction to perform film deposition. The latter type has such advantages as a reduced tendency for contamination of the substrate surface compared with the former type; but when the number of deposition chambers increases, there are the problems that gravity and elongation of the substrate cause wrinkles to occur in the surface of the substrate, or the substrate undulates in the width direction, or droops downward.
In order to resolve such problems, it has been proposed that an intermediate chamber be placed between two deposition chambers positioned in the center of an arrangement of numerous other deposition chambers, and that at this place a side edge position control (EPC) roller, which is in contact with the substrate surface across the entire surface in the width direction of the substrate, be provided. However, normally film deposition is performed at comparatively high temperatures, and if such a stainless steel EPC roller were placed between deposition chambers, such problems as the occurrence of rapid cooling of the substrate and folding wrinkles may occur.
Further, in order to prevent folding wrinkles in the substrate due to the EPC roller in the intermediate chamber, it has been proposed that the EPC roller in the intermediate chamber be eliminated, and that an edge portion of the substrate be gripped by a gripping roller and transported. However, to the extent that restraints on the substrate by the EPC roller in the intermediate chamber are removed, the effects of variation in the initial properties of the substrate itself are more readily exerted. This problem becomes prominent when the number of deposition chambers in a line is increased and the line length is extended in order to raise the production efficiency of the line; the amount of meandering in the height direction of the substrate during transport increases, and variation in the deposition positions on the film becomes larger.
Further, in the initial period of film deposition, all the prescribed thin film layers cannot be deposited on the portion of the substrate positioned from the first deposition chamber to the last deposition chamber. Hence, during the time until the substrate portion on which film is deposited in the first deposition chamber reaches the takeup core (that is, the length of one entire film pass), the properties of the substrate on which all the prescribed thin film layers have been deposited change. Consequently, the prescribed target height of the substrate, over the length from the feeding position to the takeup position in this film deposition initial period, increases or decreases in the width direction. Also, the substrate must be transported over a long period of time until the substrate height converges on the prescribed height.